Grouping transponders

ABSTRACT

Methods and systems of processing transponder signals received from transponders to identify the transponders are provided. A first signal including a first code and a first identifier may be received from a first transponder. The first identifier is written to the first transponder by an RFID writer when the first transponder is placed proximate to the RFID writer, and the first identifier is used to associate transponders with a first user. A second signal including a second code and the first identifier may be received from a second transponder. The first identifier is also written to the second transponder by the RFID writer when the second transponder is placed proximate to the RFID writer. The first and second transponders are associated with the first user based on receiving the first identifier from both the first and second transponders.

BACKGROUND

Many businesses, such as supermarkets, place barcodes on products forsale to identify the products at checkout. However, at checkout, eachproduct barcode must be located, orientated to the barcode scanner, andthen individually scanned by the barcode scanner. This process cansometimes cause significant delays and long checkout lines.Additionally, sometimes for large items, it is difficult to even findthe attached barcode. Further, barcodes sometimes won't scan and thus,the cashier has to manually enter the code into the computer.Nonetheless, customers may get frustrated with long lines at checkoutand decide not to purchase the items they came for originally, therebycausing the business to lose business.

SUMMARY

To address the above issues, an RFID system is provided which allows forscanning of multiple transponders (e.g., RFID tags) at the same time.Each of a plurality of users selects a different RFID writer. Each RFIDwriter has a unique identifier so that when a user selects items he isinterested in, the RFID writer writes the unique identifier to items'transponders selected by the user. When the user is ready to check out,an RFID reader may read the transponders of the user-selected itemssimultaneously. Because the user's RFID writer writes an identifier thatis different than other RFID writers, the RFID reader can distinguishbetween the user's selected items from other items (e.g., items fromanother user in the checkout line).

In one embodiment, a method of processing transponder signals receivedfrom transponders to identify the transponders is provided. A firstsignal including a first code and a first identifier may be receivedfrom a first transponder. The first identifier is written to the firsttransponder by an RFID writer when the first transponder is placedproximate to the RFID writer, and the first identifier is used toassociate transponders with a first user. A second signal including asecond code and the first identifier may be received from a secondtransponder. The first identifier is also written to the secondtransponder by the RFID writer when the second transponder is placedproximate to the RFID writer. The first and second transponders areassociated with the first user based on receiving the first identifierfrom both the first and second transponders.

In another embodiment, an RFID reader may include an antenna to receivetransponder signals, and a processing logic coupled to the antenna. Theprocessing logic is configured to receive, from a first transponder, afirst signal comprising a first code and a first identifier. The firstidentifier is written to the first transponder by an RFID writer whenthe first transponder is placed proximate to the RFID writer, and thefirst identifier is used to associate transponders with a first user.The processing logic is configured to receive, from a secondtransponder, a second signal comprising a second code and the firstidentifier. The first identifier is also written to the secondtransponder by the RFID writer when the second transponder is placedproximate to the RFID writer. The first and second transponders areassociated with the first user based on receiving the first identifierfrom both the first and second transponders.

In yet another embodiment, a communication system is provided. Thecommunication system may include a first RFID writer and a second RFIDwriter. The first RFID writer may be configured to be associated with afirst user and to write a first identifier to transponders that comeinto a range of the first RFID writer. The second RFID writer may beconfigured to be associated with a second user and to write a secondidentifier to transponders that come into a range of the second RFIDwriter. A RFID reader may receive, from a first transponder, a firstsignal comprising the first identifier; receive, from a secondtransponder, a second signal comprising the first identifier; andreceive, from a third transponder, a third signal comprising the secondidentifier. The RFID reader may group the first transponder and secondtransponder as being associated with a first user due to beingassociated with the first identifier. The RFID reader may associate thethird transponder with a second user due to being associated with thesecond identifier.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and features of the invention can be better understood withreference to the drawings described below, and the claims. The drawingsare not necessarily to scale, emphasis instead generally being placedupon illustrating the principles of embodiments of the invention. In thedrawings, like numerals are used to indicate like parts throughout thevarious views.

FIG. 1 illustrates a method of operating an RFID system employing RFIDwriters in accordance with one embodiment.

FIG. 2 illustrates an example of a system employing multiple RFIDwriters according to one embodiment.

FIG. 3 illustrates a diagram of a system of an RFID writer writing totransponders within the RFID writer range, according to one embodiment.

FIG. 4 illustrates a system for reading transponders having a uniqueidentifier associated with a user according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Various examples of the invention will now be described. The followingdescription provides specific details for a thorough understanding andenabling description of these examples. One skilled in the art willunderstand, however, that the invention may be practiced without many ofthese details. Additionally, some well-known structures or functions maynot be shown or described in detail, so as to avoid unnecessarilyobscuring the relevant description.

The terminology used in the description presented below is intended tobe interpreted in its broadest reasonable manner, even though it isbeing used in conjunction with a detailed description of certainspecific examples of the invention. Certain terms may even be emphasizedbelow; however, any terminology intended to be interpreted in anyrestricted manner will be overtly and specifically defined as such inthis Detailed Description section.

Examples of the invention include various methods and apparatuses forwriting a unique identifier to a set of transponders (e.g.,radio-frequency identification (RFID) tags) to associate the set oftransponders with a specific user (e.g., a customer at a store). Thisallows users to have their respective associated items bedistinguishable from each other. For example, a customer may enter astore and select a personal RFID writer. The customer then selects itemsthe customer wants to purchase and places such items proximate to thecustomer's RFID writer. The RFID writer then writes a unique identifierto the transponder of each item. This unique identifier is onlyassociated with the customer's RFID writer to distinguish the customer'sselected products from other item in the store. In this regard, when acustomer “checks out” at the store, all items with transponders havingthe customer's associated unique identifier will be purchased by thecustomer. Other items that inadvertently get scanned that may have adifferent identifier are immediately known to not have been selected bythe customer and thus, the customer may not be charged for such item.

Examples of the invention find ready application in settings where RFIDtags are placed on products for sale. These settings may include, forexample, supermarkets, retail stores, hardware stores, and any otherstores that have products that typically are scanned individually atcheckout. It should be understood that, while examples of the presentinvention are discussed herein with regard to shopping by a customer,the present invention may not be so limited and could be applied tovarious other applications.

FIG. 1 illustrates a method 50 of operating an RFID system with RFIDwriters in accordance with one embodiment. At 52, a user enters alocation and selects a first RFID writer. The location may include aplurality of RFID writers to accommodate a plurality of users. Each userselects a different RFID writer so that no user has the same RFIDwriter, and because each RFID writer is configured to write a differentidentifier to transponders, each user is associated with a uniqueidentifier.

It should be understood that the term “user” may be any person or devicewhich selects items that have transponders. In one embodiment, a usermay be a customer in a store.

Additionally, it should be understood that a transponder may be anydevice which is configured to transmit a code to a wireless reader, suchas an RFID reader. In one embodiment, a transponder is an RFID tag,which may be used to automatically identify objects. RFID tags aregenerally placed on items using an automatic tag applicator, and thenthe items are identified by one or more RFID readers.

Regardless, the first RFID writer selected by the user is placedproximate to the user. In one embodiment, the first RFID writer isplaced on a shopping cart/basket associated with the user. The firstRFID writer may be placed in a central location of the shopping cart orbasket, such as on a base portion of the shopping cart or basket, sothat the range of the RFID writer does not significantly extend beyondthe limits of the shopping cart or basket. This allows for each RFIDwriter to only be associated with one shopping cart or basket and notoverlap with other RFID writers. In other embodiments, the RFID writermay be placed at any other location, such as other locations in theshopping cart or basket (e.g., on the handle), on the user (e.g., on theuser's key chain), or any other location proximate to the user so thatthe user can browse and select items throughout the location/store whilebeing in possession of the RFID writer.

At 54, a user selects an item (e.g., products for sale in a store) andplaces the item proximate to the user's RFID writer (i.e., the firstRFID writer). Each selected item may have a transponder attached theretoor associated therewith. A user can select the item by moving the itemfrom a first location (e.g., a store shelf) to the user's shopping cartor basket (or other location) so that the item's transponder isproximate (e.g., within one to twelve inches) to the first RFID writerof the user. Regardless, when the user places the transponder of theitem proximate to the RFID writer (e.g., within a range of one to twelveinches), the first RFID writer then writes the unique identifier to thetransponder. The transponder then not only has the code identifyingspecifics of the item, but also the unique identifier which isassociated with the user. The item is then associated with the userthrough the item's transponder.

As mentioned above, a location or store can have multiple users and RFIDwriters as long as each RFID writer is configured to write a differentidentifier for each user. FIG. 2 illustrates an example of a system 100employing multiple RFID writers 104 according to one embodiment. Atleast three users 108 are illustrated as shopping in a store 102. Eachuser 108, 108′, 108″ has selected three RFID writers 104, 104′, 104″,respectively, and a shopping cart or basket 114. A first RFID writer 104is associated with a first customer 108, a second RFID writer 104′ isassociated with a second customer 108′, and a third RFID writer 104″ isassociated with a third customer 108″. Each RFID writer is configured towrite a unique identifier to transponders 106 when the transponders areselected by the customers and placed proximate to the RFID writer (e.g.,within the range 112 of the closest RFID writer), as discussed above.This allows a customer to select items when shopping (or performing someother function) and have the transponders of the customer's items have acommon unique identifier that is different than the identifiers writtento transponders for other customers. In this regard, when a user “checksout” at the store, all items with transponders having that user's uniqueidentifier will be purchased by the user, but not any other items.

It should be noted that in FIG. 2, the RIFD writer may be located atmultiple locations on the shopping cart or basket 114. For example, thefirst RFID writer 104 is placed on top of a central portion the shoppingcart or basket. This allows the customer 108 to place the object next tofirst RFID writer 104 and then drop the object in the cart/basket. Inanother embodiment illustrated in FIG. 2, the second RFID writer 104′ isplaced on top of the cart/basket 114 and on a portion of the cart/basket114 that is closest to the user 108′. This allows the user 108′ to haveRFID writer 104′ within a short, proximate distance relative to the user108′ when the user 108′ is shopping. In a third embodiment illustratedin FIG. 2, the third RFID writer 104″ is placed at a central location ofthe cart/basket. In this way, the range 112 of the third RFID writer104″ does not substantially extend outside of the cart/basket 114.Additionally, the range 112 may be such that a user simply places theitem in the cart/basket and the RFID writer automatically writes to thetransponders placed therein. It should be understood that the RFIDwriter 104 may be placed at any other location in the cart/basket 114 orat some other location on another object/person.

Referring back to FIG. 1, at 56, the first RFID writer writes a firstidentifier to the transponder when the transponder becomes proximate tothe first RFID writer, such as when the transponder is placed withinrange 112 of the first RFID writer. As mentioned above, each RFID writerhas a range whereby the RFID writer can write to a transponder. In oneembodiment, range 112 of each RFID writer may be between one inch totwelve inches. Additionally, the frequency of each RFID writer may bebetween 50 KHz to 5 MHz. In one embodiment, the frequency of each RFIDwriter may be 125 KHz. Each RFID writer may not write the uniqueidentifier to any transponders which are outside the RFID range.Operation of the RFID writer is illustrated in FIG. 3, in accordancewith one embodiment.

FIG. 3 illustrates a diagram of a system of an RFID writer 104 writingto transponders 106 within the RFID writer range 112 of a user 108,according to one embodiment. RFID writer 104 includes an antenna, atransceiver 314, a read/write module 316, and a unique identifier 318stored in memory. As illustrated in FIG. 3, transponder 106′ is withinRFID range 112, while transponders 106′, 106″ are outside of range 112.The transponders of FIG. 3 include memory 206 where a code associatedwith the transponder is stored. The code of each transponder identifiesthe item it is attached thereto. For example, a transponder attached toa shirt has a code which identifies the shirt and other data associatedwith the shirt, such as the shirt price, an SKU number, and/or any otherinformation about the shirt. The transponder code is capable of beingmodified to add or change the data therein. In one embodiment, a uniqueidentifier may be added as a prefix to the code of the transponder bythe RFID writer. In another embodiment, the unique identifier does notmodify the code but instead is saved as an additional code in thetransponder. Regardless, when an RFID reader queries the transponder,the transponder may transmit back to the RFID reader both the code andthe unique identifier.

The antenna of the RFID writer is designed to transmit a signal to atransponder which instructs the transponder to write the uniqueidentifier to the transponder, such as a prefix to the previously-storedcode. The transponders may be “passive” RFID tags or “active” RFID tags.Passive RFID tags are a type of transponder that does not contain theirown power source or transmitter. When radio waves from the RFID writerreach the transponder's antenna, the energy is converted by thetransponder's antenna into electricity that can power up the microchipin the tag (typically via inductive coupling). The passive RIFD tag isthen able to receive and store the unique identifier to memory at theRFID tag by modulating the RFID reader's electromagnetic waves. “Active”RFID tags have their own power source and transmitter. The power source,usually a battery, is used to run the microchip's circuitry and tobroadcast a signal to an RFID reader. Passive RFID tags do not have asgreat a range as active RFID tags, but it should be understood thateither type of transponder may be employed in the present application.

The read/write module 316 may be employed by the transponder to receivethe unique identifier 318 from the RFID writer 104 and uses theinductive energy from the RFID writer to write the unique identifier tothe transponder when the transponder is within the RFID writer range112. For example, in FIG. 3, transponder 106′ has been placed within theRFID writer range 112 and thus, memory 206′ is written with uniqueidentifier 318 of RFID writer 104. Transponder 106″ is outside of theRFID range 112 and thus, the RFID writer 104 does not write to suchtransponder. Similarly, transponders 106 in the shopping cart or basket114 but outside of range 112 may not be actively written to while in theshopping cart or basket. However, prior to placing transponders 106 inthe shopping cart, transponders 106 may have been placed proximate tothe RFID writer 104 for a predetermined time period. As such,transponders 106 in the shopping cart or basket 114 have identifier 318written to memory 206.

The unique identifier remains on the transponders 106 so that an RFIDreader (302 of FIG. 4) can read the transponder identifier 318 and thus,remains on the transponder until another RFID writer writes over theidentifier or if the transponder's memory 206 is erased.

It should be understood that the RFID writer 104 may be a RFIDreader/writer that is configured to not only write to transponders butmay also read the transponders.

Referring back to FIG. 1, at 58, the user may continue to add items tohis shopping cart or basket 114. For each additional items selected bythe user, steps 54 and 56 may be completed, namely that the item isselected and placed proximate to the RFID writer so the writer can writethe same unique identifier 318 to the transponders of the additionalitems. This allows the same user (i.e., the first user) to have a cartor basket 114 of items with transponders having the same uniqueidentifier (i.e., the first identifier). No other users (i.e., a seconduser, third user, etc.) in the store or location have items withtransponders having an identifier (i.e., a second identifier, thirdidentifier, etc.) other than the first identifier.

Steps 60-72 are discussed below in conjunction with FIG. 4. FIG. 4illustrates a system 300 for reading transponders having a uniqueidentifier according to an embodiment. The system 300 may include anRFID reader 302 and at least one transponder 106 with the uniqueidentifier. FIG. 4 illustrates four transponders 106 each having thesame unique identifier 318 written thereto.

At step 60 of FIG. 1, the RFID reader 302 receives the unique identifier318 (i.e., the first identifier). In one embodiment, an antenna of theRFID writer 104 wirelessly transmits the unique identifier 318 to theRFID reader 302. Upon receipt, the transceiver 308 of the RIFD reader302 may route the first identifier 318 to the processor 310 which thensaves the first identifier 318 into memory 312. All other identifiersassociated with other users that are stored in memory 312 are erased. Inthis regard, the RFID reader 302 identifies the first identifier 318 asassociated with the first user that is currently “checking out.” Inanother embodiment, a cashier or other person 320 may manually enter thefirst identifier 318 to the RFID reader 302 or a computer 301 associatedtherewith. Regardless, the first identifier 318 is stored into memory312 and may be accessed by logic 306.

Referring back to FIG. 1, at step 62, the RFID reader 302 reads one ofthe transponders 106 in the user's shopping cart or basket 114. When anitem having a transponder is placed near the RFID reader, thetransponder receives electromagnetic signals from the RFID reader. Inresponse to these electromagnetic signals, the transponder generatesradio waves with a pattern identifying the transponder. The RFIDreader's antenna receives these radio waves and transmits them to theRFID tag reader module 304, which interprets the radio waves todetermine the data that the radio waves contain. Such data may include acode indicating the identity of the object as well as any identifiersappended to the code (e.g., as a prefix). The RFID reader maycommunication the received code with a database 322 connected to theRFID reader and/or computer 301 via a network 321. The database mayinclude the codes related to the objects which the transponders 106 areattached. When the RFID reader reads the codes from the transponders106, the RFID reader may look up the codes in the database. In oneembodiment, the database may be resident on the RFID reader.

At step 64 of FIG. 1, the RFID reader determines if the data receivedfrom a first transponder includes an identifier. To determine this, forexample, the RFID reader determines if the data has a prefix attached tothe transponder code. This identifier prefix may have a starting datastring which would indicate to the RFID reader (at the RFID tag readermodule 304) that an identifier is included in the transmission. Theidentifier is then extracted from the data transmission by being thedata located between the prefix starting data string to a prefixtermination data string according to one embodiment. The extractedidentifier then may be transmitted to logic 306 of the RFID reader 302,which compares the extracted identifier from data transmitted from thefirst transponder with the first identifier received from the RFIDwriter. If the RFID reader logic 306 determines that the transpondercontains the first identifier, the method 50 may proceed to step 66;otherwise, the method 50 may continue to step 68 and may optionallyprovide an alert to the RFID reader operator.

At step 66 of FIG. 1, if the RFID reader's logic 306 determines from thecomparison that the extracted identifier and the first identifier storedin the RFID reader memory 312 are the same, the RFID reader determinesthat the first transponder contains the first identifier 318 and thus,is associated with the first user. The first transponder is thenassigned an “approved” status so that the item associated with the firsttransponder is added to a purchasing transaction. Data associated withthe first transponder, such as the identity of the associated item, theprice of the associated item or any other information about the itemassociated with the first transponder, may be transmitted to computer301 (e.g., a cash register computing device) for further processing. Forexample, the item may be added to the checkout session so that the storecan add the item to the purchase transaction list.

At step 68, the RFID reader (or computer 301) may mark the firsttransponder as having been read so that it is not read again by the RFIDreader. To that end, the RFID reader may store the transponderidentification code to memory 312 and/or transmit the transponderidentification code to computer 301. This way, if the RFID readeraccidentally scans the transponder again, the RFID reader recognizesthat the transponder identification code is one that has already beenscanned and thus, will not duplicate the item for the purchasetransaction during the checkout session of the user.

Steps 62 through 68 may be repeated for all transponders within the RFIDrange of the RFID reader 302 that have not been read by the RFID reader.Thus, at step 70, the RFID reader 302 determines if any transpondershave not been read by the RFID reader, and if not, the method 50 mayreturn to step 62. Otherwise, the RFID reader 302 may indicate (e.g.,via an audible or visual alert, via a message to computer 301, etc.)that the scanning for the checkout session for the first user hascompleted. The RFID reader 302 may transmit a list of items that werescanned and marked as “approved” to computer 301.

Thus, in light of the above, transponders, such as RFID tags, may beread when in a user's shopping cart or basket 114 so that eachindividual item associated with the transponders do not have to beindividually handled by a checkout personnel. Transponders may bescanned by the RFID reader and the ones having the user's assignedidentifier written thereto are then added to the purchase transaction.

Unless the context clearly requires otherwise, throughout thedescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof, means any connection or coupling,either direct or indirect, between two or more elements; the coupling ofconnection between the elements can be physical, logical, or acombination thereof. Additionally, the words “herein,” “above,” “below,”and words of similar import, when used in this application, shall referto this application as a whole and not to any particular portions ofthis application. Where the context permits, words in the above DetailedDescription using the singular or plural number may also include theplural or singular number respectively. The word “or,” in reference to alist of two or more items, covers all of the following interpretationsof the word: any of the items in the list, all of the items in the list,and any combination of the items in the list.

The above detailed description of embodiments of the invention is notintended to be exhaustive or to limit the invention to the precise formdisclosed above. While specific embodiments of, and examples for, theinvention are described above for illustrative purposes, variousequivalent modifications are possible within the scope of the invention,as those skilled in the relevant art will recognize. For example, whileprocesses or blocks are presented in a given order, alternativeembodiments may perform routines having steps, or employ systems havingblocks, in a different order, and some processes or blocks may bedeleted, moved, added, subdivided, combined, and/or modified to providealternative or sub-combinations. Each of these processes or blocks maybe implemented in a variety of different ways. Also, while processes orblocks are at times shown as being performed in series, these processesor blocks may instead be performed in parallel, or may be performed atdifferent times. Further any specific numbers noted herein are onlyexamples: alternative implementations may employ differing values orranges.

The teachings of the invention provided herein can be applied to othersystems, not necessarily the system described above. The elements andacts of the various embodiments described above can be combined toprovide further embodiments.

Any patents and applications and other references noted above, includingany that may be listed in accompanying filing papers, are incorporatedherein by reference. Aspects of the invention can be modified, ifnecessary, to employ the systems, functions, and concepts of the variousreferences described above to provide yet further embodiments of theinvention.

These and other changes can be made to the invention in light of theabove Detailed Description. While the above description describescertain embodiments of the invention, and describes the best modecontemplated, no matter how detailed the above appears in text, theinvention can be practiced in many ways. Details of the system may varyconsiderably in its implementation details, while still beingencompassed by the invention disclosed herein. As noted above,particular terminology used when describing certain features or aspectsof the invention should not be taken to imply that the terminology isbeing redefined herein to be restricted to any specific characteristics,features, or aspects of the invention with which that terminology isassociated. In general, the terms used in the following claims shouldnot be construed to limit the invention to the specific embodimentsdisclosed in the specification, unless the above Detailed Descriptionsection explicitly defines such terms. Accordingly, the actual scope ofthe invention encompasses not only the disclosed embodiments, but alsoall equivalent ways of practicing or implementing the invention underthe claims.

While certain aspects of the invention are presented below in certainclaim forms, the inventors contemplate the various aspects of theinvention in any number of claim forms. For example, while only oneaspect of the invention may be recited as a means-plus-function claimunder 35 U.S.C sec. 112, sixth paragraph, other aspects may likewise beembodied as a means-plus-function claim, or in other forms, such asbeing embodied in a computer-readable medium. (Any claims intended to betreated under 35 U.S.C. §112, 6 will begin with the words “means for”.)Accordingly, the inventors reserve the right to add additional claimsafter filing the application to pursue such additional claim forms forother aspects of the invention.

What is claimed is:
 1. A method of processing transponder signals received from transponders to identify the transponders, the method comprising: receiving, from a first transponder, a first signal comprising a first code and a first identifier, wherein the first identifier is written to the first transponder by a first RFID writer when the first transponder is placed proximate to the first RFID writer, and wherein the first identifier is used to associate transponders with a first user; receiving, from a second transponder, a second signal comprising a second code and the first identifier, wherein the first identifier is also written to the second transponder by the first RFID writer when the second transponder is placed proximate to the first RFID writer; and associating the first and second transponders with the first user based on the receiving the first identifier from both the first and second transponders.
 2. The method of claim 1, further comprising: receiving, from a third transponder, a third signal comprising a third code and a second identifier, wherein the second identifier is written to the third transponder by a second RFID writer when the third transponder is placed proximate to the second RFID writer, and wherein the second identifier is used to associate transponders with a second user; and identifying that the third transponder is associated with the second user instead of the first user based on the third transponder having the second identifier written by the second RFID writer rather than the first RFID writer.
 3. The method of claim 2, further comprising: receiving, from a fourth transponder, a fourth signal comprising a fourth code and the second identifier, wherein the second identifier is written to the fourth transponder by the second RFID writer when the fourth transponder is placed proximate to the second RFID writer; and identifying that the fourth transponder is associated with the second user.
 4. The method of claim 1, wherein the associating the first and second transponders with the first user comprises identifying that the first and second transponders are grouped together due to containing the first identifier and are, thus, both associated with the first user.
 5. The method of claim 1, further comprising: providing a plurality of RFID writers comprising the first RFID writer so that the first user selects the first RFID writer prior to selecting at least one item; allowing the first user to select a first item having the first transponder attached thereto; and writing the first identifier to the first transponder in response to the first item being selected by the user.
 6. The method of claim 1, wherein the allowing the first user to select a first item comprises allowing the first user to move the item into the range of the first RFID writer.
 7. The method of claim 6, wherein the range of the first RFID writer comprises a range between about one inch and about twelve inches.
 8. The method of claim 7, wherein the RFID writer is removably attachable to a shopping cart or basket.
 9. The method of claim 6, wherein the first RFID writer has a frequency of about 125 KHz.
 10. The method of claim 1, wherein the first identifier is written to the first transponder by the first RFID writer prior to the receiving the first signal from the first transponder.
 11. The method of claim 1, wherein the first code comprises data identifying a first item and the second code comprises data identifying a second item, wherein the first transponder is attached to the first item and the second transponder is attached to the second item.
 12. The method of claim 1, wherein the first identifier is attached to the first code as a prefix to the first code.
 13. The method of claim 1, further comprising receiving the first identifier from the first RFID writer prior to the receiving the first signal.
 14. The method of claim 1, further comprising scanning for transponders comprising the first identifier; and identifying all transponders comprising the first identifier.
 15. An radio frequency identification (RFID) system, comprising: an antenna to receive transponder signals; a processing logic coupled to the antenna, the processing logic configured to: receive, from a first transponder, a first signal comprising a first code and a first identifier, wherein the first identifier is written to the first transponder by a first RFID writer when the first transponder is placed proximate to the first RFID writer, and wherein the first identifier is used to associate transponders with a first user; receive, from a second transponder, a second signal comprising a second code and the first identifier, wherein the first identifier is also written to the second transponder by the first RFID writer when the second transponder is placed proximate to the first RFID writer; and associate the first and second transponders with the first user based on the first identifiers returned by the first and second transponders.
 16. The radio frequency identification system of claim 15, wherein the processing logic is further configured to: receive, from a third transponder, a third signal comprising a third code and a second identifier, wherein the second identifier is written to the third transponder by a second RFID writer when the third transponder is placed proximate to the second RFID writer, and wherein the second identifier is used to associate transponders with a second user; and identify that the third transponder is associated with the second user instead of the first user based on the third transponder having the second identifier written by the second RFID writer rather than the first RFID writer.
 17. The radio frequency identification system of claim 15, wherein the processing logic is further configured to: receive, from a fourth transponder, a fourth signal comprising a fourth code and the second identifier, wherein the second identifier is written to the fourth transponder by the second RFID writer when the fourth transponder is placed proximate to the second RFID writer; and identify that the fourth transponder is associated with the second user.
 18. The radio frequency identification system of claim 15, wherein the first identifier is attached to the first code so that the first identifier comprises a prefix to the first code.
 19. The radio frequency identification system of claim 15, wherein the processing logic is further configured to receive the first identifier from the first RFID writer.
 20. A communication system comprising a first RFID writer configured to be associated with a first user and to write a first identifier to transponders that come into a range of the first RFID writer; a second RFID writer configured to be associated with a second user and to write a second identifier to transponders that come into a range of the second RFID writer; wherein a RFID reader: receives, from a first transponder, a first signal comprising the first identifier; receives, from a second transponder, a second signal comprising the first identifier; receives, from a third transponder, a third signal comprising the second identifier; and groups the first transponder and second transponder as being associated with a first user due to being associated with the first identifier and the third transponder as being associated with a second user due to being associated with the second identifier. 